Movement and Motor Control

Question 1

What is the basic unit needed to perform any movement?

Answer 1

• which muscle to use: learned
• 1a afferent receptors: length, muscle spindles
• 1b afferent receptors: tension, golgi tendon organs

Question 2

What is meant by a motor unit?

Answer 2

every muscle fibre and one alpha motor neuron

Question 3

What is an alpha motor neuron?

Answer 3

• always excitatory

- receive mono/polysynaptic inputs from the peripheral and CNS

Question 4

What do muscle spindles do?

Answer 4

• detect length of a muscle

- buried within extrafusal muscle fibres

Question 5

What happens during the stretch of a muscle?

Answer 5

• 1a afferent neurons are activated

- tension builds in tendons which activate 1b afferent neurons

Question 6

What happens during the contraction of a muscle?

Answer 6

• no activation of 1a afferent fibres

- activation of 1b afferent fibres

Question 7

What is a reflex?

Answer 7

involuntary response to a stimulus which requires the integrity of the NS, which may involve cardiac, skeletal or smooth muscle

Question 8

What does a reflex arc involve?

Answer 8

a receptor, afferent neuron, synapse, motor neuron and an effector

Question 9

What does reciprocal innervation mean?

Answer 9

simultaneous activation (contraction) of on muscle and inhibition (relaxing) of the antagonist muscle during a reflex

Question 10

What does the stretch reflex do?

Answer 10

• helps the compensation of additional loads
• both mono and polysynaptic pathways
  1. collateral from 1a excites inhibitory neutron
  2. inhibitory interneuron inhibits alpha motor neuron to antagonist muscle
  3. antagonist muscle relaxes (reciprocal innervation)

Question 11

What does the cross extensor reflex do?

Answer 11

• helps body maintain balance
• one muscle contracts and the other relaxes
• what happens in the one limb, the opposite happens in the contralateral limb

Question 12

What is the function of the muscle spindle?

Answer 12

compensates for additional loads, causes a reflex contraction

Question 13

What does the golgi tendon reflex do?

Answer 13

protects the muscle from heavy loads
protective mechanism
drop the load

Question 14

What would happen if the golgi tendon reflex was disabled?

Answer 14

you would damage your muscle because you’re carrying too much weight

Question 15

What is the motor cortex?

Answer 15

part of the cerebral cortex where nerve pulled originate and initiate voluntary muscular activity

Question 16

What is the motor homunculus?

Answer 16

motor representation of the brain

Question 17

What is the difference between the motor and sensory homunculus?

Answer 17

no genitalia on the motor cortex surface

Question 18

What is the corticospinal tract?

Answer 18

primary pathway that leaves the area of the motor cortex to innervate with neurons in the spinal cord

Question 19

What does the dorsal lateral corticospinal tract consist of?

Answer 19

• crosses at the brain stem
• crossed tract
• fine and gross motor movement
• contralateral alpha motor neurons
• 80-90% of axons

Question 20

What does the ventral corticospinal tract consist of?

Answer 20

• uncrossed tract
• gross motor movements
• bilateral alpha motor neurons
• 10-20% of axons

Question 21

What does a positive babinski reflex mean?

Answer 21

• healthy young child, lack of descending inhibition on spinal motor neurons
• in an adult, a damaged corticospinal tract

Question 22

What does a negative babinski reflex mean?

Answer 22

healthy young adult with an intact corticospinal tract

Question 23

What does the extrapyramidal system contain?

Answer 23

cerebellum, basal ganglia, substantia nigra

Question 24

What does the cerebellum do?

Answer 24

control motor coordination, timing of movement, balance and muscle tone

Question 25

What are major deficits of a cerebellar patient? (cerebral disease)

Answer 25

• hypotonia: decreased muscle tone
• dysarthia: slurred speech
• ataxia: can’t move properly
• dystermia: shaky movements
• intention tremor: tremor occurs only when you make a movement

Question 26

What are the major functions of the basal ganglia?

Answer 26

• located deep within the cerebral hemispheres
• consists of sub thalamic nucleus and substantia nigra
• controls cognition, movement, coordination and voluntary movement

Question 27

What are symptoms associated with damage to the basal ganglia?

Answer 27

• atheotosis
• hemibalism
• increased muscle tone
• dyskinesia
• resting tremor

Question 28

What does the substantia nigra do?

Answer 28

inhibitory influence on a # of motor systems

Question 29

What are the main symptoms of Parkinson’s disease?

Answer 29

• unblinking
• resting tremor
• ridgity-both muscles contracting/ relaxing (no movement)
• slowness and poverty of movement

Question 30

What is the primary cause of Parkinson’s disease?

Answer 30

• loss of neurons in the substantia nigra

- lack of dopamine

Question 31

How are the symptoms of Parkinson’s disease treated?

Answer 31

• giving the patient dopamine
• use to take out the basal ganglia
• thalamic nucleus stimulation
• gene and stem cell therapy